The present invention relates to a motor driven cylindrical brush for a cleaning apparatus having a cylindrical brush member with bristle filling projecting beyond it, and with a contact surface for a drive belt, and with a bearing spindle, the spindle ends of which project beyond the brush member and are disposed in a brush housing.
Brushes of this type are used, for example, in vacuum cleaner nozzles for cleaning floors, especially textile floor coverings. Via the drive belt, the rotary motion of a drive motor, preferably an electric motor, of the cleaning apparatus is transmitted to the brush member. The belt contact surface is convexly curved in the longitudinal direction of the brush member, so that the relevant brush member section forms a pulley, which ensures that the drive belt, during brush operation, maintains its central position relative to the brush member section. The tufts of bristles of the bristle filling projecting beyond the brush member extend linearly or helically to the axis of the brush member. When the brush is in use, the projecting ends of the tufts of bristles penetrate the surface of the floor coverings which are to be cleaned. Thus, the dirt is released from the floor covering, is picked up by the suction stream of the cleaning apparatus, and is carried to a filtering dust collection receptacle of the vacuum cleaner.
The tufts of bristles are inserted and anchored in holes which extend approximately radially to the brush member. Also known are bristle fillings in which the tufts of bristles are inserted in a separate strip-like holder. These holders are inserted into grooves which extend axially or helically on the brush member. In such brushes, however, the brush member consists of a large number of component parts, such as the brush member, the bearing spindle, and the holders for the tufts of bristles, so that these brushes are extremely complicated and expensive. Thus, for economic reasons, in apparatus or equipment for domestic use, brushes are used which are made in one piece from wood, plastic, or metal. When the brush member consists of thermoplastic material, and is produced by injection molding, the holes for receiving the tufts of bristles can be made simultaneously with the brush member. The tufts of bristles are anchored in the holes with wire retainers, which pass through one end of the tuft of bristles and have projecting ends thereof pushed under pressure against the side walls of the holes. Brushes of this type can be manufactured at low cost in automatic and semi-automatic production systems. Frequently, brushes of this type are unsteady in operation and are out of true, which can only be compensated for by subsequent dynamic balancing. These measures are complicated and time-consuming, and thus make the brush manufacture more expensive. Moreover, the lack of trueness cannot always be remedied fully, which can result in considerable bearing loading. The unsteady running is created by a change in length of the brush member in the course of being filled with bristles, which is caused by the fact that the brush member is extended somewhat during the fastening of the tufts of bristles in the relevant holes, as a consequence of material compression, thus resulting in buckling.
It is an object of the present invention to design a brush of the aforementioned general type in such a way that any buckling occurring when the bristle filling is attached in the brush member, and caused by length changes, and consequently any unsteady running, are fully avoided.